Help with relays please

[canuck750]

I am trying to finish off the electrical connections on my 1975 Ducati 860 GT build. I have a new wire harness I made up thanks to 'Swooshdave' sending me an original one to copy.

I made a color drawing of the original wiring diagram (it is for both the kick start GT and electric start GTE) and all is good until I get to the headlight bucket.

When I received the bike all the electrical inside the headlight bucket had been cut up and Honda L and R switch gear spliced in.

The three electrical devices inside the headlight bucket; lighting relay, horn relay? and a cut off switch?? are in very poor shape and I do't think are usable.

I want to fit new Bosch relays for the headlight H and L circuits and the Horn and whatever the other 'thing' is that connects to the pair of transducers.

This is an overall view of the wiring diagram:



And this the front half with my questions about fitting modern relays and how to wire the new relay(s), what original wire to what terminal on the relay?? The original headlight relay is one unit, I thought two relays would be required, one for both the low and high beam? Also wonder why three wires connect together to the power side? The device between the horn button and horn hi/lo switch, is that a relay and again can I use a stock Bosch 4 or 5 pin relay?

And lastly what is the device the transducers are fed through? some kind of switch or another relay??



The back half of the diagram



Thanks in advance for any help you guys can provide, electrickery is my Achilles heal

[RinkRat II]

  Somebody smarter than me (Roy) should be along shortly, but, looks to me the part you ask"is that a relay" is a trigger for a cdi or magneto setup. I see no distributor in the wiring diagram and it leads me to believe this has a mag that gets triggered to send the spark thru the transducers to the plugs.   

     Paul B

[Antietam Classic Cycle]

Any photos of the mystery devices? The three-legged thing sort of looks like a zener diode.

[LesP]

Its a splitter for the transducers but might contain a d̶i̶o̶d̶e̶  resistor.

[canuck750]

Any photos of the mystery devices? The three-legged thing sort of looks like a zener diode.

I will take some pictures tomorrow of the devices and post them

[Kiwi_Roy]

I'm having trouble getting a decent printout that I can study but I think any 4 0r 5 pin relay will do

Re "is this a relay?"
I agree with Les P the three legged device is just a pair of diodes to keep the two transducers apart
I assume the switch they are powered by is the kill switch.

[canuck750]

I'm having trouble getting a decent printout that I can study but I think any 4 0r 5 pin relay will do

Will get back

THANKS!

I could email you a better file tomorrow if you pm me your email.

[Kiwi_Roy]

I usually use a 5 pin relay for the headlight my thinking is if it's not high beam it should be low beam
Could you scratch on the schematic what each of the switches is for.

[canuck750]

Will do

The right hand CEV switch has the turn signals and off/on switch. My bike is a kick start only GT model so no starter button on the switch, the wiring diagram shows the starter motor option and on the electric foot model the starter button is on the left hand switch on the top right corner.



The left hand CEV switch has the lights On/Off rocker, High and Low bean rocker, Push to Flash high beam button and Push Horn button.



The as-found nest



I googled the three device part numbers that sit inside the headlight bucket:

The "Horn device" is still available from a couple sources





The "Flash relay" looks like this







I can't find a stock picture of the device connected to the transducers  I think its this thing, clear plastic case, a bunch of wires soldered to it
but I found a link to a picture of it "Engine Stop relay"

https://www.ducaticlassics.com/ducati/096038223/engine-stop-relay

[RinkRat II]

         So much for my original theory! Looks as your Engine stop relay is just that. Wired to the ignition switch, the engine run switch and to the transducers. it also seems to have a set of diodes to keep power from back- flowing from one transducer to the other. Any common numbers on the relay itself ? Mfgr ? 

  Paul B

[canuck750]

         So much for my original theory! Looks as your Engine stop relay is just that. Wired to the ignition switch, the engine run switch and to the transducers. it also seems to have a set of diodes to keep power from back- flowing from one transducer to the other. Any common numbers on the relay itself ? Mfgr ? 

  Paul B

I found a picture on line of the stock ignition relay - manual calls it a "Transducer Distributor", what has been installed on my bike is not stock!

Kiwi Roy is looking into it for me, believes it to be a couple silicone diodes and a resistor.

[canuck750]

I found this picture on a web forum of an original 860 GT headlight bucket, the device I am looking for bottom right - "Engine Stop Relay part # 096038223"

[RinkRat II]

 Cool! Looks pretty straight forward, power in, Light blue/purple wire. Resistor, diode to each green wire to transducers. Now to figure out the value of the resistor and build it with $3.00 worth of Radio shack components.

     Paul B



        https://www.digikey.com/en/resources/conversion-calculators/conversion-calculator-resistor-color-code-4-band

[Kiwi_Roy]

It looks like the resistor might be Orange White Orange 39K or is it Orange White Red 3.9K?
I don't think the value would be that critical its just supplying a logic signal not any significant power, I doubt there is enough energy there to burn anything out at 12 Volts

If you have the old unit just measure the resistor, have someone with a Ducati measure theirs or give a better reading of the colour bands, the first 3 are important but the tolerance is not.

What is that relay looking device you have in your hand, is that a relay or is it the resistor and two diodes?

A two pole relay could do the same as the two diodes, I think its just a digital On/Off signal to the two ignition modules

[canuck750]

It looks like the resistor might be Orange White Orange 39K or is it Orange White Red 3.9K?
I don't think the value would be that critical its just supplying a logic signal not any significant power, I doubt there is enough energy there to burn anything out at 12 Volts

I don't have an original but by enlarging the picture the multi coloured drum is wide orange stripe, white stripe, thin orange stripe and thin yellow stripe.

the smaller two parts look to be the same, the one I can read has '375' on it.

Do you think if I went to an electronic components store with the picture they could match up the components?

[RinkRat II]

   Not only that but you could probably $sweet talk$ one of them to build it for you

     Paul B

[canuck750]

   Not only that but you could probably $sweet talk$ one of them to build it for you

     Paul B

I stopped in at a local electronic component shop with the photo of what the unit should look like and the wiring diagram, they sold me a 39K resistor (393) and a pair of 3A diodes, all for $3.20 tax in, hopefully it works.